Transducers can be actuators, sensors, electric power generation elements, etc. that perform conversion between mechanical energy and electrical energy. Alternatively, transducers can be speakers, microphones, etc. that perform conversion between acoustic energy and electrical energy. Polymer materials such as dielectric elastomers are useful for configuring transducers that are high in flexibility, small in size and light in weight.
An actuator may be configured by, for example, arranging a pair of electrodes on both thickness direction sides of a dielectric film that is formed of a dielectric elastomer. In an actuator of this type, electrostatic attractive force between the electrodes increases with an increase of the voltage that is applied between the electrodes, so that the dielectric film that is sandwiched between the electrodes is compressed in the thickness direction and the thickness thereof is reduced. As a result of the reduction of the film thickness, the dielectric film correspondingly expands in the direction parallel with the electrode plane. When the voltage that is applied between the electrodes is reduced, on the other hand, electrostatic attractive force decreases so that the compressive force that is acted on the dielectric film in the thickness direction is reduced and the thickness thereof increases as a result of the elastic restoring force thereof. As a result of the increase of the film thickness, the dielectric film correspondingly contracts in the direction parallel with the electrode plane. Thus, the actuator can drive an object to be driven by the expansion and contraction of the dielectric film. As the dielectric film material, silicone rubbers, acrylic rubbers, nitrile rubbers, urethane rubbers, etc. are used (see, for example, Patent Documents 1 and 2).